1、Introducing the Specifications of the Metro Ethernet Forum,* MEF 10 * replaced MEF 1 and MEF 5,MEF 2 Requirements and Framework for Ethernet Service Protection MEF 3Circuit Emulation Service Definitions, Framework and Requirements in Metro Ethernet Networks MEF 4 Metro Ethernet Network Architecture

2、Framework Part 1: Generic Framework MEF 6Metro Ethernet Services Definitions Phase I MEF 7 EMS-NMS Information Model MEF 8Implementation Agreement for the Emulation of PDH Circuitsover Metro Ethernet Networks MEF 9 Abstract Test Suite for Ethernet Services at the UNI MEF 10 Ethernet Services Attribu

3、tes Phase I MEF 11 User Network Interface (UNI) Requirements and Framework MEF 12Metro Ethernet Network Architecture Framework Part 2: Ethernet Services Layer MEF 13 User Network Interface (UNI) Type 1 Implementation Agreement MEF 14 Abstract Test Suite for Ethernet Services at the UNI MEF 15Require

4、ments for Management of Metro Ethernet Phase 1 Network Elements MEF 16 Ethernet Local Management Interface,This Presentation,Purpose This presentation is intended as an introduction and companion to both the MEF 3 and MEF 8 Specifications These are the two principal specifications relating to servic

5、es that carry Circuit Emulation/TM traffic across Carrier Ethernet Audience It is intended for Product Marketing, Engineering staff of member companies, for members of other standards bodies, Enterprise networking staff, and service providers who Would like a quick overview of the specifications Pla

6、n to read the specifications in detail Other Documents Presentations of the other specifications and an overview of all specifications is available on the MEF web site Other materials such as white papers and case studies are also available,MEF Specifications Overview,Audience,Equipment Manufacturer

7、s supporting devices that provide Circuit Emulation over Carrier Ethernet Services.Useful for Service Providers architecting their systems.,Purpose,Circuit Emulation Service “tunnels” TDM traffic through a Metro Ethernet network allowing inclusion of legacy networks within a Carrier Ethernet environ

8、ment,Purpose,Gives precise instructions for implementing interoperable CES equipment that reliably transport TDM circuits across Metro Ethernet Networks while meeting the required performance of circuit emulated TDM services as defined in ITU-T and ANSI TDM standards,Circuit Emulation Service Defini

9、tions, Framework and Requirements in Metro Ethernet Networks,MEF 3,Implementation Agreement for the Emulation of PDH Circuits over Metro Ethernet Networks,MEF 8,Technical Committee Service Area,Audience,Equipment Manufacturers supporting devices that provide Circuit Emulation over Carrier Ethernet S

10、ervices.Useful for Service Providers architecting their systems.,Technical Committee Service Area,MEF 3: CES Framework & RequirementMEF 8: CES Implementation Agreement,Industrys first formal definition of CES standards over Ethernet A services description Types of TDM services offered over Metro Eth

11、ernet, PDH and SONET/SDH DS1E1, DS3/E3, OC-3/STM-1, OC-12/STM-4 A requirement document Comprehensive CES requirements for providing TDM services over Ethernet SLA service quality parameters as specified by the ITU for TDM services An implementation agreement for Ethernet Practical agreement as to ho

12、w to implement the CES over Ethernet,TDM Circuits (e.g. T1/E1 Lines),What is Circuit Emulation Service over Carrier Ethernet?,Circuit Emulation Service “tunnels” TDM traffic through a Metro Ethernet network packet network “emulates” a circuit-switched network, re-creating the TDM circuit at the far

13、end invisible to TDM source and destination equipment runs on a standard Ethernet Line Service (E-Line),TDM Pipe,Metro Ethernet Network,TDM Circuits (e.g. T1/E1 Lines),MEF 3 TDM Circuit Emulation,Support Traditional PDH/SONET/SDH hand-offs to existing customer voice equipment Allow Interworking onto

14、 Ethernet EVCS across the MEN.,Types: 1)Unstructured - all bits in must be sent across to the destination 2) Structured - Requires only sending TDM payloads not the over head,Circuit Emulation Services Relationship to the Metro Ethernet Network,CES functions in relation to those specified by the MEF

15、 for the MEN,Functions Defined,TSP - Optional TDM mux/demux function prior to Ethernet interworking IWF - Interworking function of TDM to Ethernet frames ECDX - Identifier function for proper forwarding and demultiplexing EFTF Addressing and FCS functions.,Functions applied,ECDX as shown is effectiv

16、ely a multiplexing function allowing multiple CES circuits to share a single EVC,MEN,Functional Layering, and mapping onto encapsulation headers,Treats the MEN as a “virtual wire” between two TDM networks,Customer Premises,Customer Premises,Metro Ethernet Network,MEF Service Definitions,TDM Line Ser

17、vice (T-Line): Application: Leased line replacement,CESoETH,Ethernet UNI,Ethernet UNI,Ethernet,E-Line Service,Ethernet,TDM,TDM,CES IWF,CES IWF,TDM subscriber demarcation,TDM subscriber demarcation,Service Provider Network,PSTN,Customer Premises,Metro Ethernet Network,MEF Service Definitions,TDM Acce

18、ss Line Service (TALS): Application: Access to a remote network (e.g. PSTN),CESoETH,Ethernet UNI,Ethernet UNI,Ethernet,E-Line Service,Ethernet,TDM,TDM,CES IWF,CES IWF,TDM subscriber demarcation,TDM Network Interface,Service Provider Network,Customer Premises,Customer Premises,Metro Ethernet Network,

19、MEF Service Definitions,Customer-Operated CES: Application: Toll-bypass,CESoETH,Ethernet UNI and subscriber demarcation,Ethernet UNI and subscriber demarcation,Ethernet,E-Line Service,Ethernet,TDM,TDM,CES IWF,CES IWF,Service Provider Network,Structured Vs Unstructured CES,Structured Removes the TDM

20、overhead,TDM services supported (MEF 3),MEN CoS Performance Parameters,To ensure proper CES IWF operation service quality: Ethernet Frame Delay should be minimized to meet MEF 5 defined parameters Ethernet Frame Delay Variation MEN EVCS jitter up to 10 ms max Ethernet Frame Loss ESR and SESR should

21、meet TDM requirements Network availability should meet 99.95% TDM requirement,PDH Interoperability Agreement MEF 8,Specifies Interoperability requirements for: Connectivity Timing Signaling MEN performance criteria MEN services OAM,Emulated Circuit Identifier,ECID identifies the emulated circuit bei

22、ng carried. Separates the identification of the emulated circuit from the Ethernet layer, allowing the MEN operator to multiplex several emulated circuits across a single EVC where required. This is added by the ECDX.,CESoETH control word,Provides sequencing and signaling of defects such as AIS of t

23、he TDM circuit, or packet loss detected in the MEN. This is added by the CES IWF.,Standards for Synchronization,E1 standards (2.048 Mbps) Traffic interface (G.823, Table 2) 18 s over 1000s,T1 standards (1.544 Mbps) Traffic interface(T1.403, section 6.3.1.2) 8.4 s over 900s 18 s over 24 hours,Central

24、 Office,Remote Terminal,CESoP IWF,CESoP IWF,T1/E1,Max. end-to-end wander (traffic interface) 18 ms,CES induced wander 18 ms,PRS,PSTN,Customer Premises,TDM Equipment,PSN,T1/E1,Timing,Synchronous services require timing be provided Line, through, external or internal timing mode options Applies to str

25、ucture aware only Synchronization. the clock used to play out the data at the TDM-bound IWF must be the same frequency as the clock used to input the data at the MEN-bound IWF, otherwise frame slips will occur over time,Timing options,TDM line timing use the clock from the incoming TDM line External

26、 timing use an external reference clock source Free run timing use a free-running oscillator Ethernet line timing recovering the clock from the Ethernet interface,Signaling,Structure Aware CESoETH must provide signaling CE Common Channel Signaling (CCS) Can be carried within the emulated service dat

27、a CE Common Channel Signaling (CAS) Must be handled separately for Nx64 service- Encoding Format for CAS Note must have a separate Control Word from the Data, but can share same ECID,Performance Monitoring,Facility Data Link May monitor but not change DS1 Extended Super Frame message data Errored Da

28、ta CESoETH should be capable of monitoring Frame Error ratio,MEN Service & SLA Requirements,MEN service quality assurance is critical to maintain consistent quality of the carried TDM service SLA service quality parameters should support to those specified by the ITU for TDM services Nx64 Services r

29、equire CAS Signaling in MEN SDH/SONET requires pointer adjustments in MEN Specified MEN Quality Parameters: Frame Delay: 25ms Jitter (Delay Variation): 10ms Frame Loss/Errors Ratio (FER) For SONET/SDH: Errored Seconds (ES) Severely Errored Sec (SES) Background block SES (BFER),Frame Delay Defined,Th

30、e time required to transmit a service frame from source to destination across the MEN.,Measured from 1st bit in to last bit out,Frame Delay Variation Defined,The difference in delay of two service frames.,Metro Ethernet,Metro Ethernet,Network,Network,UNI to UNI,UNI to UNI,first bit in,first bit in,t

31、ime,CE,CE,CE,CE,Frame,Frame,Delay,Delay Variation1,Frame 1,Frame 1 last bit out,first bit in,Frame 2,Frame 2 Last bit out,Frame,Delay Variation 2,Frame Loss Defined,Frame loss is a measure of the number of lost service frames inside the MEN. Frame loss ratio is % = # frames lost / # frames sent,Metr

32、o Ethernet,Metro Ethernet,Network,Network,UNI to UNI,UNI to UNI,5000 frames in,CE,CE,CE,CE,4995 frames out,time,5 frames lost/or received as errored 0.1% Frame Loss Ratio (5/5000),MEN Frame Loss Errors PDH Limits,PDH ES PDH SES,Other MEN Parameters,Emulated Circuit Availability 99.95% Emulated Circu

33、it Restoral 50 ms Suggested MEN Bandwidth increments 100 kbps,MEF Services OAM,Alarms Misconnection alarm (section 6.6.1) Loss of Frames alarm (section 6.6.2) Late Frames alarm (section 6.6.3) Malformed Frames alarm (section 6.6.4) Jitter buffer overrun alarm (section 6.6.5),Management Alarms,Miscon

34、nection Alarms MEN defects: Stray Frames Must be discarded CES IWF must check the Ethernet Source address field Should report an alarm if stray frames persists above set threshold (Default 2.5 seconds) Alarm should be cleared if no stray frames received for a configurable period of time (Default 10 seconds) Mechanism for detection of lost frames Must Not be affected by reception of stray frames,Management Alarm Statistics Counters,MEN bound Frames transmitted Payload octets transmitted TDM bound Frames received Payload oc